Photoelectric control device with rotatable housing for adjustable light control to the photosensitive element



TATABLE HOUSING FOR ADJUSTABLE LIGHT CONTROL TO THE PHOTOSENSITIVEELEMENT Richard L. Thompson, Hendersonville, N.C., assignor to GeneralElectric Company, a corporation of New York Filed Apr. 14, 1966, Ser.No. 542,599

' 11 Claims. (Cl. Z50-239) The present invention relates tophotoelectric control devices, andjmore particularly concerns devices ofthis type .incorporating light sensitiveelements for controlling theloperation orf-,apparatus Isuch as street lighting luminaires inaccordance with the light level of ambient light.

In known types. of outdoor luminaires, photoelectric control units areremovably attached tothe exterior of the luminaire housing inlelectrical connection with the Iluminaireoperating circuit, and withthe light sensitive element fixed within the photoelectric controlhousing exposed to ambient light through a transparent opening in 4thehousing. Certain drawbacks have been encountered in such use f knowntypes ofphotoelectric control devices.4 For one thing, in large scalemanufacture of photoelectriccontrol devices the uniformity of the unitsin terms of their sensitivity to light levels cannot Abe readilycontrolled. Moreover, it well known that the sensitivity, electricaloutput and other characteristics of photoelectric cells tend to changeover a prolonged period, and consequently the response of the cells toambient light levels changes with time. As a result, Vthe luminaires ina particular area may be turned on or ott at widely different times, orparticular luminaires may change their on or olf times even at the samelight level with the of the light sensitiveV element, but entirelyYsatisfactory since they made the masked portions inoperable and changed-the size resulting in nonuniform operating characteristics Vand otherundesirable results. Furthermore,'the use of such shields increased thecost of the units. It is an object of the present invention to provide aphotoelectric control device which overcomes the above disadvantages ofknown types of devices.

It is'a particular object of the invention to provide a photoelectriccontrol device which may be adjusted in its response to light levels.

It is another object ofthe invention to provide a photoelectric controldevice of the above type which is simple in construction andeconomically manufactured, and which may be readily' and accuratelyadjusted and calibrated at any time to provide for its response at anyparticular light level.

Other objects and advantages will become apparent from the followingdescription and the appended claims.

With the above objects in view, the present invention relates to aphotoelectric control device comprising a base member having oppositesides, electrical switching means mounted on one side of the basemember, electrioal contact means on the opposite side of the base memberelectrically connected to the switching means, photoelectric meansmounted on the one side of the base member in electrical connection withthe switching means, the photoelectric means comprising a lightsensitive element lying substantially in a plane, and an opaque housingoverlying the one side of the base member and enclosing the switchingmeans and photoelectric means thereon, the housing having a transparentwindow adjacent the photoelectric means arranged so that exterior lightpasses into the interior along the window axis and is incident on thelight sensitive element, the housing being releasably secured to Ithebase member and being rotatably 3,408,501 Patented oct. 29, 196s ACf?adjustable thereon for varying the angle of the plane of the lightsensitive element relative to the aforementioned window axis whereby thesensitivity of the light sensitive element to the incident light may beadjusted to a predetermined level.

The invention will be better understood from the following descriptiontaken in conjunction with the accompanying drawing in which:

FIGURE 1 is a side view in elevation of a photoelectric control deviceembodying the invention, showing the light sensitive element in oneadjusted position of the device; j

FIGURE 2 is a view similar to that of FIGURE 1 showing the deviceadjusted to a different position;

FIGURE 3 is a partly sectional view of the photoelectric control deviceshowing the components in the interior thereof;

FIGURE 4 is a bottom plan view of the FIGURE 3 device;

FIG'URE 5 is a fragmentary detailed view in exploded form of theadjustable securing means of the FIGURE 3 device; and

FIGURE 6 is a cross-sectional view of the parts shown in FIGURE 5 inassembled form.

Referring now to the drawing, and particularly -to FIG- URE l, there isshown a photoelectric control device of a type adapted for use withstreet lighting luminaires and comprising a generally cup-shaped opaquehousing hood portion 1a having an integral larger diameter. Housing URE1 arrangement than with the FIGURE 2 arrangement.

As shown in FIGURE 3, which is a view taken along the line 3 3 of FIG.

4, the electrical components disclosed within housing 1, includingphotoelectric cell 4 and relay 5, are mounted on base 6 which, inaccordance with the invention, is secured to housing 1 so as to becomponents (not shown) of the photoelectric control device are alsosecured to the upper side of base member 6. The electrical circuit ofwhich photoelectric cell 4, relay and the other electrical componentsform a part are electrically connected to plugin contact prongs 9projecting downwardly from the bottom side of base member 6 which areadapted to be inserted into a socket in a luminaire housing (or otherapparatus) with which the photoelectric control device is to beoperatively associated. Constructional details of the mounting of relay5 and other parts on base member 6 are disclosed in co-pendingapplication Ser. No. 542,612, filed Apr. 14, 1966 in the name of I R.Burch and assigned to the same assignee as the present application, anddo not form a part of the present invention.

As seen in the bottom view of FIGURE 4, base member 6 is generally ofdisk-shaped circular form and has an outer diameter slightly smallerthan the inner diameter of the skirt portion 1b of housing 1 and thusreadily nests within that portion and is freely rotatable therein. Thephotoelectric cell and other electrical parts mounted on base member 6are all spaced inwardly from the margin of the base member a sufficientdistance to clear shoulder 1c of housing 1 when base member 6 is placedin assembly within housing 1, as seen in FIGURE 3. Thus, housing 1 restsat its annular shoulder 1c on the upper marginal surface of base member6 and is rotatable thereon.

The periphery of base member 6 is formed at opposite sides witharc-shaped cutout portions or recesses 10 and 11 into which project,respectively, ledges 12 and 13 formed in base member 6 intermediate theopposite surfaces of the latter and coextensive with length of therespective recesses 10, 11. Arranged at diametrically opposite sides ofskirt portion 1b adjacent shoulder 1c are stop members 14 and 15 whichlie within recesses 10 and 11, respectively, and which abut against basemember 6 at opposite ends of the respective recesses when housing 1 isturned in opposite directions relative to base member 6. Stop members14, 15, which may be integral with housing 1 or otherwise securedthereto, define the limits of a range of rotational adjustments ofhousing 1 on base member 6. Typically, the arrangement of stop members14, 15 is such that when housing 1 is in the extreme position shown inFIGURE 4, light sensitive element 3 directly faces window 2 as seen inFIGURE 1, i.e., is in a plane normal to the axis of window 2; and whenhousing 1 is rotated relative to base member 6 in clockwise direction asviewed in FIGURE 4 until it is in the other extreme position where stopmembers 14, 15 reach the opposite ends of recesses 10, 11, window 2 ismoved suciently away from light sensitive element 3 that the latter haslittle or no external light incident thereon. At intermediate pointsbetween such extreme positions of housing 1 relative to base member 6,the surface of light sensitive element 3 is oriented at different anglesto the axis of window 2 and the light beam entering therethrough, thusproviding different intensities of light on light sensitive element 3and thereby different levels of response of the latter to enteringlight, depending on the particular angular position of light sensitiveelement 3.

To hold housing 1 in the desired adjusted position, there are providedoppositely arranged screws 16, 17 threadably received in holes 18, 19formed in housing 1 adjacent stop members 14, 15 in which screws 16, 17may be tightened, with washers 16a, 17a bridging ledges 12, 13 and stopmembers 14, 15 respectively. Such tightening of screws 16, 17effectively clamps housing 1 to base member 6 to prevent relativerotation thereof and maintains window 2 in the desired adjusted angularposition relative to light sensitive element 3.

As seen in FIGURE 6,`the surface of stop member 14 is arranged to beapproximately at the level of the lower surface of ledge 12 in theassembly (with corresponding arrangement of stop member 15 and ledge 13)so that washer 16a uniformly engages and clamps these surfaces whenscrew 16 is tightened. The surface of stop member 14 and the adjoiningportion of the inner surface of housing wall 1b are recessed as shown inFIG- URE 5 to provide a retaining seat for washer 16a and to facilitateassembly of the latter in the proper position in register with hole 18.

Spaced indicator markings 20 on the inner surface of skirt portion 1band index pointer 21 on the 'bottom surface of ybase member 6 serve toindicate the relative rotational position of base member 6 with respectto housing 1 and thereby facilitate calibration of the unit. Thus,markings 20 may be calibrated in terms of footcandles so that theparticular scale line 20 with which pointer 21 is aligned indicates thefootcandle level of ambient light at which the photoelectric controlunit turns on the lighting apparatus which it controls. For example,assuming that with the adjustment shown in FIGURE 5 light sensitiveelement 3 directly faces window 2, the characteristics of the unit would|be such lat the particular light level that the electric currentgenerated in the photocell is sufficient to operate the associated relay5 and thereby switch off the lighting apparatus at the footcandle levelindicated. Should it be desired to switch off the lighting apparatus ata higher level of ambient light, screws 16, 17 are loosened, housing 1is rotated relative to base member 6 to a position where pointer 21indicates such higher footcandle level, and screws 16, 17 areretightened. In this newly adjusted position, the axis of lightsensitive element 3 is at an angle to the axis of window 2, therebydecreasing the intensity of light incident thereon at the particulartime. It would thus require the ambient light to reach a higher level'before the relay 5 would be actuated to turn the lighting appaartusoif. Conversely, the lighting apparatus would vbe turned on at a higherambient light level in the newly adjusted position, in other words,would be turned on earlier in the evening than with the originalposition of the photocell unit relative to the housing window.

By virtue of the features described, the photoelectric control unit ofthe invention may 'be readily calibrated at the factory using a standardillumination source so that the units produced will have uniformresponses to a particular light level. Later on after prolonged use inoperation the photoelectric control units may be readily readjusted inthe field to compensate for any variation in response therein due toaging conditions. Users of the device are also provided thereby withmeans whereby they can select any desired illumination level for turn-onor turn-off of the controlled equipment.

While the present invention has been described with reference toparticular embodiments thereof, it will be understood that numerousmodifications may be made by those skilled in the art without actuallydeparting from the scope of the invention. Therefore, the appendedclaims are intended to cover all such equivalent variations as comewithin the true spirit and scope of the invention.

What I claim as new and desire to secure by Letters Patent of the UnitedStates is:

1. A photoelectric control device comprising, in com- Ibination, a basemember having opposite sides, photoelectric means mounted 0n one side ofsaid base member and having a light sensitive element extending in aplane, an opaque housing covering said one side of said base member andleaving said opposite side thereof open to the exterior of said housing,said housing having a light transmitting window through which externallight may enter the interior of said housing, said housing beingadjustable relative to said base member between a position wherein saidlight sensitive element directly faces said window so as to besubstantially normal to the axis thereof, and a position wherein theplane of said light sensitive element is at a different angle to saidwindow axis, and securing means releasably holding said housing and saidbase member in adjusted position, whereby the response of saidphotoelectric means to the illumination level of the entering light maybe varied.

2. A device as defined in claim 1, said Ibase member and said housinghaving mutually engaging circular portions arranged coaxial with oneanother, and being coaxially rotatable relative to one another.

3. A device as defined in claim 2, including electrical contact meanselectrically connected to said photoelectric means and projectingoutwardly from said opposite side of said base member.

4. A device as defined in claim 2, said base member being substantiallydisk-shaped, said housing having an annular shoulder resting on saidbase member in rotatable sliding engagement therewith.

5. A device as defined in claim 4, the periphery of said base memberhaving recess means therein, said securing means 'being arranged in saidrecess means.

6. A device as defined in claim 4, the periphery of said Kbase memberhaving elongated recess means therein, said housing having stop meansprojecting into said recess means and coacting therewith to limit therelative movement of said base member and said housing to said differentpositions.

7. A device as defined in claim 6, wherein said securing means comprisereleasable `clamping means engageable with said base member and saidhousing.

8. A device as defined in claim 7, said base member having ledge meansprojecting into said recess means along the length thereof, saidclamping means vbeing engageable with said stop means and said ledgemeans for retaining said Ibase member and said housing in adjustedrelative position.

9. A device as defined in claim 6, wherein said recess means comprise apair of arc-shaped slots located at diametrically opposite edges ofsaidbase member.

10. A device as defined in claim 2, said housing Ibeing cup-shaped andbeing formed with an enlarged radially offset rim portion, said basemember having an outer diameter slightly smaller than the inner diameterof said housing rim portion so as to nest therein with its periphery inslidable engagement therewith.

11. A device as defined in claim 3, said photoelectric means beingadjacent a peripheral edge of said base member with its light sensitiveelement facing radially outwardly, and electrical switching meansmounted on said one side of said base member and electrically connectedto said photoelectric means and said electrical contact means.

References Cited UNITED STATES PATENTS 3,031,582. 4/1962 Benner et al.Z50-239 3,264,466 8/ 1966 Bacon 240-25 3,341,711 9/1967 Shepard Z50-239JAMES W. LAWRENCE, Primary Examiner. V. LAFRANCHI, Assistant Examiner.

1. A PHOTOELECTRIC CONTROL DEVICE COMPRISING, IN COMBINATION, A BASEMEMBER HAVING OPPOSITE SIDES, PHOTOELECTRIC MEANS MOUNTED ON ONE SIDE OFSAID BASE MEMBER AND HAVING A LIGHT SENSITIVE ELEMENT EXTENDING IN APLANE, AN OPAQUE HOUSING COVERING SAID ONE SIDE OF SAID BASE MEMBER ANDLEAVING SAID OPPOSITE SIDE THEREOF OPEN TO THE EXTERIOR OF SAID HOUSING,SAID HOUSING HAVING A LIGHT TRANSMITTING WINDOW THROUGH WHICH EXTERNALLIGHT MAY ENTER THE INTERIOR OF SAID HOUSING, SAID HOUSING BEINGADJUSTABLE RELATIVE TO SAID BASE MEMBER BETWEEN A POSITION WHEREIN SAIDLIGHT SENSITIVE ELEMENT DIRECTLY FACES SAID WINDOW SO AS TO BESUBSTANTIALLY NORMAL TO THE AXIS THEREOF, AND A POSITION WHEREIN THEPLANE OF SAID LIGHT SENSITIVE ELEMENT IS AT A DIFFERENT ANGLE TO SAIDWINDOW AXIS, AND SECURING MEANS RELEASABLY HOLDING SAID HOUSING AND SAIDBASE MEMBER IN ADJUSTED POSITION, WHEREBY THE RESPONSE OF SAIDPHOTOELECTRIC MEANS TO THE ILLUMINATION LEVEL OF THE ENTERING LIGHT MAYBE VARIED.